I laid out my thoughts on the management of hyponatremia way back in Podcast 39. Josh has weighed in here on the dDAVP clamp as well. I'd been continuing my readings on this matter, especially with some great posts from the renal fellow network (below). Then, fortuitously, I was approached by Nand Wadhwa, one of our amazing nephrologists at Stony Brook. He wanted to partner with my unit to create a euvolemic hyponatremia protocol. So in this episode, we'll discuss the use and basis of the new Euvolemic Hyponatremia Guideline.

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Eric Siegal

There is a lot of hand-waving and dogma around hyponatremia, and I think it generally serves to overcomplicate a conceptually simple problem. The key is categorization: Hypovolemic hyponatremia: The biggest concern is balancing the imperative to fluid resuscitate and maintain vascular tone against the imperative not to spike the serum sodium. That said, it’s frequently acute and rapid correction is generally pretty safe. Hypervolemic hyponatremia: Fairly difficult (although not impossible) to overcorrect because the underlying causes (cirrhosis, heart failure) are similarly difficult to correct. Euvolemic hyponatremia is the real problem. I like to break it into two categories: Stupid Patient/Clinician vs Stupid Kidneys: Stupid Kidneys: ADH is present in excess, kidneys over-respond to ADH, or osmostat is reset. Whatever the case, it’s rather difficult to over-correct because the kidneys will resist you all the way. Stupid Patient/Clinician: Water intoxication, potomania, or drug (e.g. thiazide). The kidneys are NORMAL, and once you remove the insult, the sodium will RAPIDLY normalize. BE VERY AFRAID. These are the situations where it makes sense to consider a DDAVP “clamp” or using two IV fluids to customize your infused osmolality. Whatever you do, watch the sodium like a hawk. As always, the key is history… Read more »

Eric,
This reductionism is likely part of the problem. What you have outlined seems to be the exact dogma that has been taught to all of us as we have come up through training. If it was so simple and categorization so clean cut, I (and I am sure you as a crit care director) would not see it botched so very often by the folks around you. The whole point the new thinking on hyponatremia is attempting to address is almost never does the patient fit into just one category. It is a dirty picture with many different etiologies. The reason I was approached by a nephrologist at Janus General to work with him on a protocol is that even his own colleagues were espousing the simple categorization/treatment scheme you outline with huge jumps in Na as a result. Hyponatremia is super simple if you are going to treat with fluid restriction. The second you start administering solute and volume, the simplicity ends and the situation requires a savvy clinician. Treating ICH is easy, hyponatremia not so much.

I am not remotely qualified to “peer review” this, so I have a couple of questions. Mostly regarding potassium repletion independent of sodium management.

Many hospitals have limits or rates of potassium repletion. I.e. 10 meq/hr on a floor/tele bed through a peripheral IV or 20 meq/hr in the ICU with a central line. I have become a fan of avoiding the mandatory tele/ICU bed by using the oral route.

In the ED, on a monitor, I will replete with 25 meq of Potassium Citrate/bicarbonate ORALLY q 30 minutes. This has never caused a problem that I have been able to detect either clinically or by monitor changes. I haven’t (when I have checked) overshot to hyperkalemia.

I have typically used this to get someone who has paresthesias or general weakness with a K in the 2.x range up to the 3.x range, mostly to pacify the admitting docs.

Hi Scott, I am a great fan of your show and I did enjoy the hyponatremia podcast. I would like to make the following comments: 1. The Edelman equation and its derived formulas are really essential to the understanding of the pathogenesis of all hypo- and hypernatremias. They are also central in designing the right treatment. As you rightly stated it is not enough to only look at the impact of a certain amount of a certain type of infusion on the sodium concentration. You have to do a complete “tonicity balance”, that is assessment of the sodium, potassium and water balances. The Edelman equation allows you to do exactly that. By using a tabular format (see my post at swissnephro.org) this can be done in no time. 2. The impact of the exchangeable potassium on the sodium concentration is indeed often overlooked. Diagnostically it is absolutely necessary to do both sodium AND potassium in the urine. Otherwise you really do not know what the kidney is doing tonicity wise (, the osmolality on the other hand is expendable, esp. if you are also measuring urea). Therapeutically you not only have to consider potassium supplements (oral bioavailability 100%, although you… Read more »